docs: def update_trackers(self):
          """ Updates the denormalized trackers associated with the topic instance. """
          self.posts_count = self.posts.filter(approved=True).count()
          first_post = self.posts.all().order_by('created').first()
          last_post = self.posts.filter(approved=True).order_by('-created').first()
          self.first_post = first_post
          self.last_post = last_post
          self.last_post_on = last_post.created if last_post else None
          self._simple_save()
          # Trigger the forum-level trackers update
          self.forum.update_trackers()